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Biomedical subjects

G N Akoev

Publications and source records attributed to G N Akoev.

At least 109 records · Page 6Linked to original sources
PubMedDate not supplied

Effect of low-intensity millimeter-range electromagnetic irradiation on the recovery of function in lesioned sciatic nerves in rats.

The effects of electromagnetic irradiation (EMI) of wavelength 5.6 mm (frequency 53.57 GHz) and power density 4 mW/cm2 on the recovery of function in damaged rat sciatic nerve were studied; damage was produced by nerve section followed by microsuturing. Irradiation was applied to the skin of the thigh in the area of suturing. Total action potential (TAP) recording from the nerve was used to study the functional properties of regenerating nerve fibers five months after lesioning. These experiments demonstrated that EMI had a stimulatory effect on regenerative processes in the nerve, in terms of 25-30% increases in the rate of action potential conduction along nerve fibers, with increases in TAP amplitude.

Action Potentials↗
PubMedDate not supplied

Effect of veratridine on the release of neurotrophic factors in nerve tissue cultures.

The depolarizing agent veratridine was shown to affect the level of neurotrophic substances in combined cultures of neonatal rat hippocampus and chick embryo spinal ganglia. In this experimental model, the level of neurotrophic factors in rat hippocampus explants increased as a result of increases in neuronal activity mediated by veratridine. The effects of these neurotrophins on neurite growth in the sensitive spinal ganglion neurons in the combined cultures were evaluated using morphometric methods. Neurite-stimulating effects were seen when veratridine was added to the nutritive medium at a concentration of 90 nM. Antibody to nerve growth factor blocked the action of veratridine. These results demonstrate a role for neuron activity as a regulatory mechanism controlling the expression of neurotrophins.

Animals↗
PubMedDate not supplied

Role of neurotrophic factors in adaptational processes of the nervous system.

Neurotrophic factors (NTF) are low-molecular-weight proteins which epigenetically determine neuron survival during embryogenesis and the maintenance of their morphofunctional properties in the adult organism. NTF are located in mesenchymal tissues and reach neuron bodies by means of retrograde axoplasmic transport in nerve fibers; in cell bodies, NTF increase anabolic activity, neurotransmitter synthesis, and structural protein production. Neuron cell bodies have two types of specialized receptors for binding the most common NTF, nerve growth factor (NGF). In the brain, NGF does not affect adrenergic neurons, as it does in the periphery, but acts on cholinergic neurons in the basal part of the forebrain. The forebrain plays the major role in the processes of learning, memory, and plasticity, i.e., in the entire complex of adaptational responses of the nervous system, and these may thus depend on the biological activities of substances, including NTF, in forebrain tissues. An experimental model was developed consisting of organotypic co-cultivation of rat hippocampus fragments with chick embryo dorsal root ganglia. This model was used to demonstrate that epileptiform activity in the hippocampus is associated with increases in NTF release, which can be regarded as an adaptive compensatory response to nerve cell damage occurring during convulsive activity.

Adaptation, Physiological↗
PubMedDate not supplied

[Effect of extremely high-frequency electromagnetic radiation on the function of skin sensory endings].

The specific features of skin receptor function on the sole of the hind limb of an albino rat were studied in an acute experiment. Impulse activity recorded from the solitary fibres of the tibial nerve showed that receptor units (RU) responded to mechanical stimulation of the skin. Irradiation of the skin surface by low-intensity millimeter band electromagnetic field (frequencies of 55.61 and 73 GHz) in the zone of the RU led to diminution of RU sensitivity to the mechanical stimulus. One half of the RU ceased to respond to the mechanical stimulation 25 minutes after irradiation. The other half continued responding to stimulation even after 35 minutes of irradiation, but the character of the RU response was significantly changed. A strict frequency-resonance dependence of the biological effects was revealed. It is concluded that electromagnetic radiation has a modulatory-inhibiting effect on the skin RU. The authors suggest a possible mechanism of realization of the effect of electromagnetic radiation of extremely high-frequencies and low power on the skin receptor function.

Animals↗
PubMedDate not supplied

[Regeneration of the rabbit sciatic nerve after its dissection and the use of various surgical methods].

The method of stimulation electromyography and histological methods were used to study regeneration of the sciatic nerve of a rabbit after its division and joining with epineural and perineural sutures as well as by means of a vascular allograft. Successful regeneration of the nerve occurred in both types of sutures. Implantation of a vessel induced a marked inflammatory reaction in the rabbit, which aggravated the conditions for regeneration.

Animals↗
PubMedDate not supplied

[Perception of chemical and temperature stimuli by the ampullae of Lorenzini in in skates].

Recording impulse activity in single nervous fibers, studies have been made on the effect of chemical and thermal stimuli on the activity of Lorenzini ampullae in the rays Dasyatis pastinaca and Raja clavata. Application of the diluted sea water to the opening of ampullary canal increases the discharge rate of the receptors resulting into subsequent adaptation, whereas the increase in water salinity causes opposite changes. Threshold changes in the salinity of sea water amount 1--2%. Thermal transient in the sea water at the vicinity of the opening of ampullary canal did not affect the activity of the receptors. A decrease in temperature at the vicinity of receptor cells resulted in a transient rise of the firing rate of the receptors, while the increase of temperature decreased the activity of the receptors.

Adaptation, Physiological↗